Introduction

The report aims to analyse the four pollutants observations made by 25 air quality monitors that are scattered across New Your city. The measurements were made betwenn 01-01-1990 and 31-12-2019, and the pollutants analysed here are:

ppm -> parts per million ppb -> parts per billion

Data source: NOAA Historical Air Quality

See also sql_code file to see how the database was queried.

Data Processing

Looking into the first row:

##   site_num  parameter_name concentration date_local longitude latitude
## 1     0071 Carbon monoxide      1.173684 1990-01-01 -73.98368 40.69578
## 2     0011  Sulfur dioxide     14.712500 1990-01-01 -73.94722 40.73277
## 3     0073  Sulfur dioxide     17.958333 1990-01-01 -73.90958 40.81149
## 4     0056 Carbon monoxide      1.568421 1990-01-01 -73.96661 40.75912
## 5     0063           Ozone      0.024706 1990-01-01 -74.01264 40.71149
## 6     0056 Carbon monoxide      1.608696 1990-01-01 -73.96661 40.75912

What is the sampling time period?

##          min        max
## 1 1990-01-01 2019-12-31

How many measurements were made and what are their time period?

##                parameter                   period observations
## 1        Carbon monoxide 1990-01-01 to 2019-12-31       104192
## 2         Sulfur dioxide 1990-01-01 to 2019-12-31       102677
## 3                  Ozone 1990-01-01 to 2019-12-31        50026
## 4 Nitrogen dioxide (NO2) 1990-01-01 to 2019-12-31        38892
## 5    Outdoor Temperature 1992-06-09 to 2019-12-31        21793

What is the average number of observations between 1990 and 2019?

  • On average, Carbon Dioxide had the large number of observations.
## # A tibble: 5 x 2
##   parameter_name           mean
##   <chr>                   <dbl>
## 1 Carbon monoxide [ppm]    4.76
## 2 Nitrogen dioxide [ppb]   3.59
## 3 Outdoor Temperature[°F]  2.24
## 4 Ozone [ppm]              4.57
## 5 Sulfur dioxide [ppb]     4.65

How frequent were the measurements throughout the years?

  • CO and SO2 had approximately 2500 observation per year until around the year 2000, when the total number of observations drop to around 1000.
  • O3 observations kept almost constant over the year (around 1500 observations per year) with a peak between 1999 and 2001.

## Data Analysis #### Looking for trends How the concentration of pollutants evolve over time?

  • The trend of all pollutants, but ozone, seams to decrease over time.
  • Specially Sulfur dioxide (SO2) and Ozone (O3) present regular oscillation peaks and valleys.

Have the peaks and valleys of O3 and SO2 a pattern?

  • Looking closely between 2010 and 2016, O3 presents a pattern where peaks occur round the middle of the year and valleys around the turning of the years (Figure A).
  • Figure B shows the frequency distribution of the months that presented mean concentration over 0.04 ppm of O3 (black line in Figure A) within 1990 and 2019. Clearly, monitors measure on average higher concentrations of O3 between April and September.
  • A mirror phenomena occurs when measuring SO3. Within the first and last months, monitors detect a higher concentration of SO3. For instance, Figure C show the weave-pattern of SO3 between 1990 and 1996, and Figure D shows the frequency distribution of the months that have daily average concentration above 30 ppb between 1990 and 2019.

What is the linear correlation among the parameters between 1990 and 2019?

  • CO, SO2 and NO2 have a strong correlation among themselves. That may indicate that these tree pollutants share common sources.
  • Ozone (O3) and temperature also present strong correlation. It is common knowledge that ozone is unstable substance on atmosphere pressure and high temperatures. Thus, one could expect that O3 and temperature have negative correlation, if the source of ozone were constant over the years. However, the positive correlation of 0.6 indicates the temperature is positive correlated with the amount of O3 released on New York proximity.

What are the four most relevant Ozone observations and their neighborhood?

  • Neighborhoods Financial District and Latourette Park measure consistently higher concentration of ozone than the city average.

  • The oposite is observed for the neighborhoods Bronx Park and Flatiron. #### What are the four most relevant Carbon Monoxide observations and their neighborhood?

  • Neighborhoods Tribeca and Downtown Brooklyn measure slightly higher concentration of CO than the city average.

  • The oposite is observed for the neighborhoods Midtown and Bronx Park.

What are the four most relevant Sulfur Dioxide observations and their neighborhood?

  • Neighborhoods Midtown and Flatiron District measure higher concentration of SO2 than the city average no the 90s and part of the 2000s.
  • The monitor located in Flushing detected consistently lower values than the city average.
  • The monitor located in Longwood detected SO2 concentrations around average. Around the year 2000 SO2 yearly average crosses downwards the city average.
  • The City Average decreasing trend may be biased because the monitors with historical data from the 90s to middle 2000s are different than the one that have historical data from middle 2000s on wards. However, the trends of monitors separately have a downward trend.

What are the four most relevant Nitrogen Dioxide observations and their neighborhood?

  • Midtown monitor measured consistently concentrations of NO2 above the city average.
  • Contrarily, the monitor by FLushing measured consistently yearly mean concentration below city average.
  • The monitor located in Bay Side neighborhood has data of only four years.

Geospatial Visualization

Air quality monitors across NY

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CO monitors across New York

Relative CO pollution among the neighborhoods of NY between 1990 and 2000

In the map below, the darker the red, the higher the CO average concentration in ppm between 1990 and 2000. Since the majority of the neighborhoods do not have a monitor, their CO concentration are estimated through weighted average of all the other monitors. The weights are function of the distances to the other monitors (Read more here).

The nearst monitor distance, which is displayed together of the estimation and neighborhood name, can be interpreted as a measurement of approximation occur. It is expected that, the closer a neighborhood is from a monitor, the more accurate is the estimation of the reality. Looking to the [Choropleth](https://en.wikipedia.org/wiki/Choropleth_map#:~:text=A%20choropleth%20map%20(from%20Greek,each%20area%2C%20such%20as%20population) below, it is possible to conclude:

  • Manhattan and proximity have the highest values of CO on average between 1990 and 2000.
  • Neighborhoods near to the cost (most southern) have on average the lowest concentrations of CO.
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Conclusion

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